• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.2
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• pp.80-84
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• 2002

In spite of simple and cheap cultivation method, water broadcast-seeded rice demonstrates uneven and unstable seedling establishment per unit land area and requires more herbicide and labor-input for weed control. Three experiments were conducted in a phytotron at 18$^{\circ}C$ to evaluate the adaptability of seed-mat mulching cultivation technologies in water seeded rice for the uniform seedling establishment and the inhibition of weed occurrence without herbicide application. Five different kinds of mat with different mesh sizes and fabric properties were tested. The emergence of rice was the highest in Lawn-mat treatment, being comparable with the control, in which seeds were sown without mat. The Lawn-mat also exhibited the lowest mat tension. Mat tension may influence the emergence of rice. And once it was soaked in water, it didn't maintain its original shape any more. The emergence rate of rice was the lowest in Safer-mat treatment. In Lawn-mat treatment, which was the most effective for rice emergence in the first study, the differences of emergence and seedling establishment of rice depending on the seeding position (upper, beneath, and between mats) treatments were negligible, while they were higher in dry seeds than in pre-germinated seeds treatment. The emergence as affected by the kinds of mat also showed the same trend when tested using barnyard grass. Depending on the kinds of mat, the inhibition effect of weeds was the greatest in Safer-mat and the poorest in Lawn-mat. These results strongly suggest the possibility that the uniform seedling establishment and weed management without chemical could be achieved simultaneously by seed-mat mulching through the combination of effective mat for the emergence of rice and another efficient mat for the inhibition of weed occurrence. This possibility was also tested in the field.

• Korean Journal of Weed Science
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• v.31 no.2
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• pp.175-182
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• 2011

This study was conducted to evaluate the growth inhibition of weeds and selectivity of crop species by hairy vetch residues. The growth of all the weed species was suppressed greater than 90% at the ratio 60 : 40 of hairy vetch residues and no weeds were emerged at 90 : 10 mixture in the greenhouse. It was noticed that broadleaf weed species were more suppressed compared to grass weed species. Growth of weeds was significantly reduced and the inhibition percent was increased with increasing application depths of hairy vetch mixture both in vinylhouse and in field conditions. Among the different application depths of hairy vetch mixture, 0.75 cm depth of application tended to inhibit more, but statistically no significant difference was observed between 0.5 cm and 0.75 cm application depth. The growth of weed species such as Galium spurium, Chenopodium album, Plantago asiatica, and Rumex japonicus was greatly suppressed in the vinylhouse and the growth of G. spurium, R. japonicus and Amaranthus retroflexus was suppressed significantly in the field condition. The growth inhibition of all the above mentioned sensitive weed species was approximately 80% at the application depth of 0.5 cm. Crop growth was not hampered by using the residues of hairy vetch. This study demonstrated that rotation crop residues of hairy vetch contained high allelopathic potential to different weed species without hampering the growth of crop species.

• Korean Journal of Weed Science
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• v.7 no.2
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• pp.220-235
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• 1987

The experiment was carried out to find the feasibility of using Oxyfluorfen in the paddy fields by investigating the difference of selective activity of Oxyfluorfen among rice cultivars and major paddy weed species. The dosage of Oxyfluorfen that show selective activity between rice cultivars and weed species ranged from 0.1 to 0.4kg ai/ha. The degree of growth inhibition was in order of whole-plant soaking application > root soaking application > stem bandage application, and in that case $10^{-5}$M Oxyfluorfen was treated after emergence. Especially the growth inhibition of rice cultivars and Cyperus serotinus was low, among others. Photosynthesis was severely inhibited at the Oxyfluorfen level above $10^{-4}$ M in all the tested weeds, but inhibition of respiration was not to be seen. Isolated single cells of two rice cultivars and Cyperus serotinus were tolerant to $10^{-5}$M Oxyfluorfen,but those of Echinochloa crus-galli and Sagittaria pygmaea were susceptible comparatively. The growth inhibition of suspension cultured rice cell induced by the increments of Oxyfluorfen concentration, and the degree of inhibition was higher in C.V. Mushakdanti than in C.V. Aichiasahi.

• Journal of Biosystems Engineering
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• v.21 no.1
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• pp.21-33
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• 1996

This study was to obtain basic information needed to develop the effective weed control method for the production of less polluted agricultural products by inducing viability loss of weed seeds in soil with infrared irradiation. Ceramic plates were heated by LPG with the aid of forced air and the infrared produced from plates was used as the heat source for heating soil. The soil heated in this study was sandy loam with four levels of moisture contents (0.5, 5.1, 9.1, 15.0% wb). The temperature distribution was measured at various soil depths when soil was irradiated with infrared for different irradiation time (30, 60, 90 sec). The soil depths with duration time of minimum 3 minutes over $80^circ C$, temperature inducing viability loss of weed seeds, were investigated. When the moisture content of soil was 0.5% and 5.1% wb, the soil depths which can induce viability loss of weed seeds was greatly increased with increasing irradiation time. When 30 seconds of irradiation time was applied on soil with moisture content of 9.1% or 15.0% wb, any depths of soil tested in this study was not reached to the temperature of 8$0^{\circ}C$. Generally, the soil depth being needed for viability loss of weed seeds was decreased with increasing moisture content of soil.

• Weed & Turfgrass Science
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• v.4 no.3
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• pp.243-248
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• 2015

This study was conducted to investigate the ability for weed control of the shoot extract of sorghum (Sorghum bicolor (L.) Moench) and developing a sustainable weed management in organic farming. When the dried shoot powder was mixed with soil and treated with 2 cm above the soil surface, the germination for Echinochloa crus-galli, Digitaria cilialis, Abutilon theophrasti and Amaranthus retroflexus was inhibited maxium 40%. The growth inhibition of germinated seedlings in the A. theophrasti and A. retroflexus was maxium 30% while it was less than 30% in the E. crus-galli and D. cilialis. Shoot extracts at rates above $25mg\;ml^{-1}$ was effective to inhibit germination of D. cilialis, A. theophrasti and A. retroflexus. The shoot extract concentration required for 50% of germination inhibition was $60mg\;ml^{-1}$ in the E. crus-galli, while it was less than $10mg\;ml^{-1}$ in the D. cilialis, A. theophrasti and A. retroflexus. For the foliar application, 11 adjuvants were tested at 0.5% and DOS70, TM15 and TDE7 were most effective adjuvants for the shoot extracts. DOS70 was most effective and provided up to 60% of weed control efficacy for the tested four weed species. Though herbicidal efficacy of sorghum shoot was not enough to give a proper weed control, it can be expected that long term use of sorghum shoots can provide gradual decrease in weed seeds and weed density.

• Korean Journal of Weed Science
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• v.15 no.4
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• pp.247-253
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• 1995

The herbicide butachlor [N-(butoxymethyl)-2-chloro-N-(2,6-di-methylphenyl) acetamide] is widely used by farmers as a tool for weed management of transplanted rice(Oryza sativa L.) in Taiwan. The herbicide did not stop germination of rice and weed seeds, but strongly inhibited the subsequent growth of young shoots and roots. The inhibition was also strong on established seedlings. However, they could recover to normal growth after the herbicide effect disappeared. Butachlor greatly decreased the endogenous indole-3-acetic acid (IAA) but increased the endogenous abscisic acid (ABA) contents of rice seedlings. Addition of lAA into growth medium (Hoagland's solution) partly relieved growth inhibition. Pretreatment of both gibberellic acid ($GA_3$) and IAA 24 hours before butachlor treatment almost completely alleviated the butachlor-interfere with GA and/or IAA metabolism or their action resulting in the growth inhibition of rice. Butachlor was readily absorbed by rice roots. During 24 hours of uptake experiment, 32% of the applied herbicide was absorbed. Pretreatment of the herbicide for 2 days did ncx affect the absorption. Of the absorbed herbicide, 80% remained in roots, only 20% transported into shoots, and more than 50% was metabolized to water soluble substances. Thin-layer chromatographic (TLC) analysis indicated that the Rf value of the most abundant metabolite was butachlor-glutathione conjugate. Rice, barnyardgrass (Echinochloa crus-galli (L.) Beauv.), and monochoria (Monochoria vaginalis Presl) seedlings contained relatively high level of non-protein thiols, while the glutathione S-transferase (GST) activity was found highest in rice, barnyardgrass the next, monochoria the lowest. The difference in GST activity among these species might be related to their sensitivity to butachlor.

• Korean Journal of Weed Science
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• v.15 no.2
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• pp.121-130
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• 1995

Greenhouse and laboratory studies were conducted to investigate allelopathic potential of some weed species on alfalfa(Medicago sativa L.) germination and seedling growth. In the comparison between top(leaves+stems) and root extracts, top extract exhibited greater allelopathic effects on alfalfa germination than that of root. The various weed species extract differently responded to alfalfa test species, WL-320, in terms of allelopathic effect. Top and root aqueous extracts of lambsquarter(Chenopodium album L.), giant foxtail(Setaria faberii Herrm.), redroot pigweed (Amaranthus retroflexus L.), velvetleaf(Abutilon theophrasti Medic.), crabgrass(Digitaria sanguinalis L.), canada thistle(Cirsium arvense L.) and prostrate knotweed(Polygonium aviculare L.) significantly inhibited germination, seedling length, weight, vigor, and rate of germination of alfalfa. The regression slopes of various top extracts showed that velvetleaf(b=3.69) extracts were the most inhibitory, while large crabgrass(b=2.39) extracts had the least allelopathic effect on alfalfa germination. Germination, seedling length and weight of alfalfa were inversely proportional to the concentration of dried velvetleaf extracts. Also, more of the toxic effects were observed from the dried extracts compared to the fresh extracts. Residue of velvetleaf inhibited significantly alfalfa emergence and survival percentage compared to the control. The emergence and survival percentage of alfalfa were 44%, 57% at 1.0% residue treatment, respectively. When weed residues were mixed with silica sand with incubation time, velvetleaf residue most inhibited alfalfa growth. The degree of inhibition increased as incubation time increased. An incubation for 72h caused the greatest inhibition of alfalfa growth. These results demonstrate the different allelopathic activity of weed species extracts on alfalfa and suggest that weed may affect alfalfa growth and development through the inhibitory effects of allelochemicals present in weed tissue.

• Korean Journal of Weed Science
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• v.18 no.1
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• pp.48-53
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• 1998

When rice straw was mulched, the inhibition of weed growth was observed in the barley field. This study was carried to indentify the influence of rice straw extract on germination, shoot and root growth of barley and water foxtail, according to extraction rate, temperature, growth stage, variety and soaking time. The inhibition rate of germination, shoot and root length of barley and water foxtail was higest in rice straw extract of $24^{\circ}C$, 5hours, 10%(w/v). Daerimbyeo's extract among 17 rice varieties inhibited growth of barley most, but Anjoongbyeo's was lowest. Among five growth stages, extract at seedling stages inhibited growth of barly and water foxtail most. Among 10 barley varieties, Seaolbori showed the greatest growth inhibition by rice straw extract.

• Korean Journal of Weed Science
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• v.30 no.3
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• pp.258-265
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• 2010

The effects of organic-compound fertilizer on weed control and rice growth in the transplanting rice cultivation were researched in this article. The results showed that the growth of transplanted rice was promoted (the increased rate was 10.3~27.2%), but the plant number for Echinochloa crus-galli was controlled (the inhibition rate was 50.3~89.2%), besides, small amount of organic-compound fertilizer in controlling Aneilema keisak was highly effective when the transplanted rice was treated with 125~250 kg $10a^{-1}$ organic-compound fertilizer. Moreover, E. crus-galli, Monochoria vaginalis and A. keisak were inhibited largely by increasing the water depth (1~5 cm), whereas Eleocharis kuroguwai and other sedges weeds were not effected by water depth. Compared with the temperature of $20{\sim}35^{\circ}C$, the plant occurrence of E. crus-galli and M. vaginalis at high temperature was inhibited (the inhibition rate were 75.4~92.2% and 49.5%~81.6%, respectively). When the transplanted rice was treated with the above organic-compound fertilizer after 10day, the inhibition rate of plant occurrence for E. crus-galli and M. vaginalis was 33.7% and 23.3%, respectively. Similarly, in the later period of rice growth, the plant height and the numbers of tiller grew slowly in conventional soil in comparison with the soil treated with organic-compound fertilizer. It has been found that the rice yield in experimental soil was decreased by 4%. This result in the field experiment showed that organic material contents in conventional soil were lower than that in soil which used the organic-compound fertilizer. Weed control in experimental soil showed 60.5% lower effects than that in conventional soil.

• Korean Journal of Weed Science
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• v.17 no.1
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• pp.80-93
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• 1997

Allelopathic compounds as naturally occurring herbicide have originally reported from local vegetation since B.C. 300. These compounds are known as secondary plant metabolites which released from plants into the environment often attract or repel, nourish or poison other organisms. In recent, many natural plant allelochemicals be used to attempt to biologically or ecologically control weed among worldwide weed scientists. Some allelochemicals have also used as fungicides, insecticides, and nematodicides, and were less than man-made agrochemicals to damage the global ecosystem. It makes efficient use of resources internal to the farm, relies on a minimum of purchased inputs. Some scientists selected for allelopathic activity when breeding weed-controlling cultivars of rice, sorghum, cucumber, surflower etc. Thus, this paper is focused on allelopathic compounds isolated from cultivated crop with the high potential of prospective herbicides. The most environmentally acceptable and sustainable approach to utilization of allelopathy for weed control is to develop plant cultivars with proven allelopathic characteristics. In rice accessions, there are 60 cultivars/lines which have known as allelopathic activity and some of these cultivars control weed more less 90% within certain radius of activity. These accessions are originated from 15 countries including Korea, Japan, USA, India, Philippines, Indonesia, Laos, Taiwan, Afghanistan, Mali, Pakistan, Colombia, Egypt, China, and Dom. Rep. From these cultivars, the most common allelopathic compounds identified in rice are p-Hydroxybenzoic, Vanillic, p-Coumaric, and Ferulic acids. In addition, allelopathic lines of the following crop have shown inhibition of weed growth : beet (Beta vulgaris), lupin(Lupinus spp.), com(Zea mays), Wheat(Triticum aestivum), oats(Avena spp.) peas(Pisum sativum), barley(Hordeum vulgare), rye(Secale cereale), and cucumber(Cucumis sativus). Thus, future allelopathy research must be designed its potentially phytotoxic propertices and the ecotoxic features of the allelochemicals from release to degradation ; its ecological sustainability, its allelopathic effect in early growth. stages, and selectivity properties in combination with chemical stages, and selectivity properties in combination with chemical concentrations. Also, research approach in allelopathy might be screened for highly allelopathic germplasm collection of crops, the idea being to ultimately transfer this agronomic character into improved cultivars by either conventional breeding or other genetic transfer techniques.